Rotator cuff
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2008-07-15T01:35:43Z
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/* Rotator cuff tear */
{{Refimprove|talk=y|date=June 2008}}
{{Infobox Anatomy |
Name = Rotator cuff |
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Image = Gray412.png |
Caption = Muscles on the dorsum of the scapula, and the Triceps brachii. |
Image2 = Gray521.png |
Caption2 = The scapular and circumflex arteries. |
System = |
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}}
The '''rotator cuff''' (rotor cuff) is an [[human anatomy|anatomical]] term given to the group of [[muscle]]s and their [[tendon]]s that act to stabilize the [[shoulder]]. Along with the [[teres major muscle|teres major]] and the [[deltoid muscle|deltoid]], the four muscles of the rotator cuff make up the six '''scapulohumeral''' (those that connect to the [[humerus]] and [[scapula]]) muscles of the [[human body]].
==Function==
These muscles arise from the [[scapula]] and connect to the head of the [[humerus]] forming a cuff at the shoulder joint. They are important because they hold the '''head of the humerus''' in the small and shallow [[glenoid fossa]] of the scapula. The [[glenohumeral joint]] is often likened to a [[golf ball]] sitting on a golf tee. During elevation of the arm, the rotator cuff compresses the glenohumeral joint in order to allow the large [[deltoid muscle]] to further elevate the arm. In other words, without the rotator cuff, the humeral head would ride up partially out of the glenoid fossa, lessening the efficiency of the deltoid muscle.
Some anatomists dispute the importance of the rotator cuff {{who?}}. According to them the m. biceps brachii is the key factor in keeping the bones together.{{Fact|date=June 2008}}
==Muscles composing rotator cuff==
{| class="wikitable"
| '''Muscle''' || '''Origin on scapula''' || '''Attachment on humerus''' || '''Function''' || '''Innervation'''
|-
| ''[[Supraspinatus muscle]]'' || [[supraspinous fossa]] || [[greater tubercle]] || ''[[Abduction (kinesiology)|abducts]]'' the [[arm]] || Suprascapular nerve (C5)
|-
| ''[[Infraspinatus muscle]]'' || [[infraspinous fossa]] || greater tubercle || ''[[laterally rotates]]'' the arm || Suprascapular nerve (C5-C6)
|-
| ''[[Teres minor muscle]]'' || [[lateral border]] || greater tubercle || ''laterally rotates'' the arm || Axillary nerve (C5)
|-
| ''[[Subscapularis muscle]]'' || [[subscapular fossa]] || [[lesser tubercle]] || ''[[medially rotates]]'' the [[humerus]] || Subscapular nerve (C5-C6)
|}
The [[mnemonic]] "SITS" is often used to remember the four muscles of the rotator cuff.
==Injuries==
===Rotator cuff tear===
{{main|Rotator cuff tear}}
This group of tendons can become [[Rotator cuff tear|torn]], leading to [[pain]] and restricted movement of the arm. A [[Rotator cuff tear| torn rotator cuff]] can occur following a trauma to the shoulder or it can occur through "wear and tear" of the tendons (most commonly that of the supraspinatus) under the [[acromion]]. It is an injury frequently sustained by athletes whose duties involve making repetitive throws, such as [[baseball]] [[pitcher]]s, [[American football]] [[quarterback]]s, swimmers, boxers, kayaking [[Fast bowling| fast bowlers]] in cricket and tennis players (due to their service motion). It is commonly associated with motions that require repeated overhead motions or forceful pulling motions.
===Rotator cuff impingement===
A [[systematic review]] of relevant research found that the accuracy of the physical examination is low.<ref name="pmid17720798">{{cite journal |author=Hegedus EJ, Goode A, Campbell S, ''et al'' |title=Physical Examination Tests of the Shoulder: A Systematic Review with Meta-analysis of Individual Tests |journal= |volume= |issue= |pages=80|year=2007 |pmid=17720798 |doi=10.1136/bjsm.2007.038406}}</ref> The Hawkins-Kennedy test<ref>{{cite web |url=http://www.shoulderdoc.co.uk/education/article.asp?article=580 |author=ShoulderDoc.co.uk Shoulder and Elbow Surgery | title=Hawkins-Kennedy Test|accessdate=2007-09-12 |format= |work=}} (video)</ref><ref name="Brukner14">{{cite web |url=http://www.clinicalsportsmedicine.com/chapters/14d.htm |title=Chapter 14: Shoulder Pain |accessdate=2007-08-30 |format= |work=|author=Brukner P, Khan K, Kibler WB}}</ref> has a [[sensitivity (tests)|sensitivity]] of approximately 80% to 90% for detecting impingement. The [[infraspinatus]] and [[supraspinatus]]<ref>{{cite web |url=http://www.shoulderdoc.co.uk/education/article.asp?article=582 |title=Empty Can/Full Can Test|author=ShoulderDoc.co.uk Shoulder and Elbow Surgery |accessdate=2007-09-12 |format= |work=}} (video)</ref> tests have a [[specificity (tests)|specificity]] of 80% to 90%.<ref name="pmid17720798"/>
===Treatment===
====Reduce pain and swelling====
As with all muscle injuries, [[RICE (medicine)|R.I.C.E.]] is the modality recommended by MDs, DOs, Physical Therapists, Athletic Trainers, and Chiropractors.{{Fact|date=June 2008}}
* '''''R'''est'' means ceasing movement of the affected area.
* '''''I'''cing'' uses ice to reduce inflammation.
* '''''C'''ompression'' limits the swelling.
* '''''E'''levation'' involves placing the area higher to reduce inflammation and swelling.
[[Cold compression therapy]] is very useful for all muscle tears and strains as it reduces pain and swelling. Using a cold compression therapy wrap for 15 minutes before sleeping can aid in reducing the pain which causes a restless nights sleep.{{Fact|date=June 2008}}
====Strengthening====
The rotator cuff can be strengthened to rehabilitate shoulder injuries, and prevent future ones. There are different exercises to target the individual rotator cuff muscles.
{| class="wikitable"
| '''Description''' || '''Beginning ''' || '''End'''
|-
| The most effective is the side-lying external rotation, which activates the supraspinatus, subscapularis, infraspinatus and teres minor. The side-lying external rotation involves the person selecting a [[dumbbell]] of low weight initially when first training - no more than 3 kilograms. The lifter lies on a bench sideways, with the arm next to his side and slightly flexed at the elbow. The dumbbell should then be raised towards the ceiling to a 45 degree angle, with the arm still flexed and close to the body, at a pace of two seconds up and four seconds down. The side-lying abduction does not involve the teres minor, but moderately involve the [[deltoid muscles]], making it an excellent all-round shoulder exercise. || [[Image:side-lying abduction begin.jpg|150px]] || [[Image:side-lying abduction end.jpg|150px]]
|-
| Another exercise is the propped external rotator, which targets the infraspinatus and teres minor. The lifter should sit perpendicular to the [[barbell]], with his arm flexed at 90 degrees at the elbow and the forearm resting parallel on the barbell. Again, selecting a dumbbell of modest weight if just beginning, raise the dumbbell up until the forearm points up. Slowly lower the dumbbell and repeat, exercising both arms. || [[Image:Propped external rotator begin.jpg|150px]] || [[Image:Propped external rotator end correct.jpg|150px]]
|-
| The final exercise is the lateral raise with internal rotation (LRIR). Grasping a dumbbell in each hand, the lifter should internally rotate his arm so that his extended thumbs point towards the floor - as if the lifter is emptying a drink into a bin. The lifter should then raise his arms sideways, with the thumbs still pointing downwards, until the dumbbells are just below the shoulders. The LRIR primarily targets the supraspinatus. || [[Image:LRIR begin.jpg|150px]] || [[Image:LRIR end.jpg|150px]]
|}
Strengthening the rotator cuff allows for increased loads in a variety of exercises. When [[weightlifting|weightlifters]] are unable to increase the weight they can lift on a pushing exercise (such as the [[bench press]] or [[military press]]) for an extended period of time, strengthening the rotator cuff can often allow them to begin making gains again. It also prevents future injuries to the glenohumeral joint, balancing the often-dominant internal rotators with stronger external rotators. Finally, exercising the rotator cuff can lead to improved posture, as without exercise to the [[external rotator]], the [[internal rotators]] can see a shortening, leading to tightness. This often manifests itself as rounded shoulders in the population.
====Surgery====
When the rotator cuff is torn, surgery is usually required to reattach the tendon to the bone.[http://www.orthop.washington.edu/rotatorcuff]
==Additional images==
<gallery>
Image:Shoulderjoint.PNG|Diagram of the human shoulder joint
Image:Gray810.png|Suprascapular and axillary nerves of right side, seen from behind.
Image:Gray818.png|The suprascapular, axillary, and radial nerves.
</gallery>
==References==
<references/>
==External links==
*[http://www.eurekalert.org/pub_releases/2007-04/foas-fwt041907.php Free weight training gets workers with rotator cuff injuries back on the job] Federation of American Societies for Experimental Biology
{{Muscles of upper limb}}
[[Category:Upper limb anatomy]]
[[Category:Shoulder]]
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